Avionics displays efficiently provide a vast amount of data to an aircraft pilot in a form that is intuitive and easy to understand. Among the data provided to a pilot is the aircraft's position relative to terrain, weather events and other hazards, and man-made features such as runways and terminals. Such position data can be easily provided in a graphical or map-based form, and most avionics systems currently provide such a graphical rendering of an aircraft's relative position. Key to such relative position information is the displayed symbol representative of the aircraft's position. This ownship symbol must be quickly locatable on a display. Traditionally this has been ensured by centering the ownship symbol in the map-based display and/or rendering the ownship symbol in a color that readily contrasts with other displayed colors, such as magenta or bright green. Another way of ensuring easy location of the ownship signal is to make the symbol a constant size regardless of the scale of the map-based display with which it is displayed. Although the ownship symbol greatly overstates the size of the airplane relative to the display scale, the strategy works well for in-air applications where the ownship symbol is not likely to obscure the display of nearby hazards, and where the locations of nearby hazards are not an immediate threat to safely operating the aircraft.
There are certain situations in which the fixed-size ownship symbol may not be an optimal method of displaying the location of an aircraft. Specifically, operations of an aircraft on or near the ground, such as during taxiing, take-off, approach, and landing, present a different set of challenges. Ground or surface operations place an aircraft in much closer proximity to other vehicles and structures, and the separation between other aircraft in particular is smaller. Aircraft generally have a much more restricted movement area and there is therefore a much smaller tolerance for error in movement. A fixed-size ownship symbol that overstates the size of the aircraft on the display obscures important surface traffic or obstacles that are immediately near the aircraft. Even if the ownship symbol were provided in outline form to minimize such obfuscation of nearby objects, a fixed-size ownship symbol provides potentially misleading situation awareness information with regard to separation from proximal structures and objects.
It is therefore an object of the invention to improve the situational awareness of a pilot of an aircraft by providing accurate information relative to the scale of an aircraft on an aircraft-based display.
Another object of the invention is to minimize the displayed obfuscation of hazards and traffic near an aircraft.
It is another object of the invention is to provide accurate separation information between an aircraft and nearby objects.
A feature of the invention is the simultaneous display of a fixed-size ownship symbol and an ownship symbol conformal to the scale of the rendered display during surface or ground-based aircraft operation.
An advantage of the invention is increased situational awareness during surface or ground-based aircraft operation.